1. Field of the Invention
This invention relates to a polypeptide which is transferred from the male corn earworm moth to the female during mating. After transfer, a decline in the production of sex pheromone is observed for at least 24 hours and the female becomes unattractive to males over that period of time. A continued presence of this peptide within the female serves as an effective means of insect control by rendering it permanently unattractive. The peptide is also useful in the study of insect physiology.
2. Description of the Prior Art
Insect infestation of crops is a primary cause of crop loss throughout the United States. A wide variety of chemical pesticides has been relied upon in the past to control insect pests; however, environmental concerns as well as consumer safety have led to the deregistration of many pesticides and a reluctance to use others on agricultural products which are ultimately consumed as food. As a consequence, scientists have begun to pursue the development of biological control agents which are environmentally safe both from a consumer and an agricultural point of view.
The corn earworm Helicoverpa zea (H. zea), formerly Heliothis, causes an estimated $1.2 billion in crop damage each year, therefore scientists have been exploring biocontrol methods effective for this pest.
A number of individuals have sought to exploit the natural sex attractants of insects to disrupt reproductive behavior.
Sekul et al. (J. Econ. Entomology, 1975) identified Z-11-hexadecenal, produced and released by the adult female of H. zea, and referred to the compound as a sex attractant inhibitor. The compound elicited strong sex stimulation activity in caged males; however, in field experiments, the catch of males in sticky or electric grid traps was inhibited in the presence of the compound.
Mitchell et al. (U.S. Pat. No. 4,083,995, 1978) disclosed a chemical of non-biological origin, (Z)-9-tetradecen-1-ol formate [(Z)-9-TDF], which was effective in reducing mating in corn earworm and tobacco budworm moths.
Sparks et al. (Southern Cooperative Series Bulletin, 1988) discussed Heliothis pheromones and their potential use as biocontrol agents by mating disruption.
Raina et al. (U.S. Pat. No. 5,032,567, 1991) disclosed a neuropeptide referred to as Hez-PBAN, which was isolated from H. zea females. The peptide activates pheromone biosynthesis in the moth; therefore appropriate application of this peptide may lead to the production of pheromone at inappropriate times or in inappropriate amounts, thereby upsetting the normal reproductive cycle. In addition, melanization in the larvae is also activated by Hez-PBAN, and significant mortality associated with melanization was observed in inoculated larvae.
Kingan et al. (Soc. Neurosci. Abstract 17:549, 1991) reported the discovery of pheromonostatic factors (PSFs) from accessory glands of male H. zea moths and discussed preliminary studies using accessory gland extracts.
Fraser et al. (U.S. Pat. No. 5,041,379, 1991) described Heliothis expression systems useful for the production of vaccines, antigens for immunoassay procedures, insecticides and foreign peptides or proteins. Heterologous genes controlled by a Heliothis polyhedrin promoter were inserted into a baculovirus vector for introduction into an appropriate host system for expression of the foreign DNA.